Technical Abstract:
Edwardsiella tarda is the causative agent of edwardsiellosis in warmwater fish. Cultured channel catfish (Ictalurus punctatus) are commonly susceptible to infection. The objective of the present study was to determine the lethality of a wild E. tarda strain to healthy channel catfish infected by bath immersion. The channel catfish (N=180) were separated into replicate groups of 20 and exposed to varying amounts (9.28x105cfu/mL, 1.89x107cfu/mL, 6.22x107cfu/mL and 2.97x108cfu/mL) of E. tarda in 3 L bath solutions for 30 minutes. The fish were held, 20 individuals per tank, and observed for 96 hours post infection for disease signs and mortality. The results indicated lethal infection of channel catfish can be obtained via bath immersion at 6.22 x107cfu/mL and 2.97x108cfu/mL, Cumulative mortality was observed at be 78% at 6.22x107cfu/mL and 70% at 2.97x108cfu/mL. These results suggest that healthy channel catfish are susceptible to E. tarda infection by immersion without prior mechanical skin injury.